It is well known to join two or more conduits with a tubular connecting piece by locating the conduit ends to be connected at respective openings in the connecting piece and securing said ends to the connecting piece to communicate with the respective openings. In particular, this method is used to connect thermoplastics tubes by welding the tubes to a thermoplastics connecting piece. The conduit ends required supporting whilst being secured to the connecting piece and it is known to provide this support by inserting support means into the connecting piece through one of the openings for a conduit end. Obviously, however, it has not been possible to support all of the conduits from inside the connecting piece because the support means must be withdrawn from said opening to allow the respective conduit end to be connected to the connecting piece to communicate with said opening. It is an object of the present invention to provide a method whereby all of the conduit ends can be supported from inside the connecting piece whilst they are secured to the connecting piece.